The PIC microcontroller's function is to control
the CS8900a, implement higher-level network protocols and provide
content. The 16F series PICs have 1K-4K program flash RAM to store
the software that does this. The code is written in C (as opposed
to straight assembly) for portability & readability. The variant
used is CCS PIC-C, which is, unfortunatly, not free. However, the
assembled code is included and can be x-checked against the C version
to make upgrades and modifications (for example, the MAC address,
or desired IP address, etc). Included is the low-level polling-style
Ethernet controller, simple ICMP reply (for pings), simple UDP,
and DHCP request code.